406 MHz (which this one is) is the good frequency.And it has a built-in GPS and transmits position.And it has a 121.5 MHz Homing beacon. That's allgood. Chris' vendor doesnt brag about its waterproofness,and a minimum of JIS-7 or IPX-7 (3', 30 minutes)would be required to use it while bobbing on thesurface. I can't get into the McMurdo (mfg) website(http://www.mcmurdo.co.uk/) to check.